This document discusses the properties of radioisotopes. It explains that radioactive isotopes undergo radioactive decay by emitting one of three types of radiation (alpha, beta, gamma) until they become stable. It defines half-life as the time it takes for half of the atoms in a sample to decay. The half-life remains constant, so the activity of a sample decreases over time in a predictable way. The document also discusses the penetrating abilities of different types of radiation and how they can pass through varying materials. It notes that isotopes of the same element have the same chemical properties but may differ physically based on their number of neutrons.

1. PROPERTIES
OF
RADIO­
ISOTOPES
by:­ Aman Verma

2. Emits Radiation
●
Radioactive isotopes are unstable so they go
into a radioactive decay emitting radiations.
●
Till they become stable
●
3 types of radiations:
Alpha particles (α)
Beta particles (β)
Gamma particles (γ)

3. Radiation

4. Half-life (t1/2)
●
●
The time taken for the activity of a
radioisotope to reach half of it's original value.
Thus activity decreases with time.

5. Half-life (t1/2)
For example, suppose we had 20,000 atoms of a radioactive
substance. If the half-life is 1 hour, how many atoms of that
substance would be left after:
Time
(after)
Number of atoms
remaining
% of atoms remaining
1 Hour (one lifetime)
10,000
50%
2 hours (Two
lifetimes)
5,000
25%
3 hours (Three
lifetimes)
2,500
12.5%

6. Half-life & Radioactivity

7. Penetration Property
●
●
Radioactive radiations have different
PENETRATING ability.
Depends on ''thickness and density'' of
material

8. Penetrating Power of Radiation
α
β
γ
n
Skin &
paper
5mm brass
6mm Al
α = alpha β = Beta
Pb & concrete
Very thick
concrete (2m)
γ = Gamma n = Neutron

9. Same Chemical properties
●
●
Isotopes of same element have same
Chemical properties.
Due to same no. of electrons in the 'Outermost
Shell'.

10. Different Physical properties
●
Differ from isotopes to isotopes.
●
Based on number of neutron.

11. Different Physical properties
●
Differ from isotopes to isotopes.
●
Based on number of neutron.